Wound release dressing



United States Patent [72] Inventors Jack H. Gardner;

Sam Rizzo, Highland Park, NJ. [211 App]. No. 666,214

[22] Filed Sept. 7, 1967 [45] Patented Sept. 15, 1970 [73] Assignee Johnson & Johnson,

a corporation of New Jersey [54] WOUND RELEASE DRESSING 13 Claims, 7 Drawing Figs.

[52] U.S. Cl 128/156 [51] lnt.Cl A61] 15/00 [50] Field ofSearch ..128/155-157 [56] References Cited UNITED STATES PATENTS 2,371,001 3/1945 Stone 128/156X 2,893,388 7/1959 Ganz 128/156 2,923,298 2/ 1960 Dockstader et al. 128/156X 2,992,644 7/1961 Platinga et al. 128/156 3,416,525 12/1968 Yeremian 128/156 Primary Examiner--L.W. Trapp Attorneys-Alexander T. Kardos, Arnold S. Worfolk and Harold L. Warner ABSTRACT: A dressing adapted to be placed over open wounds in which the dressing or at least the wound-contacting surface of the dressing is formed of a fabric having a low degree of adhesion to healing wounds, the fabric comprising a perforate fiber base, the fibers of which are coated and bonded together with a plasticized polyvinyl chloride. The

plasticizer is preferably of the polyester type, the polyester being a polyester of long chain poly basic acids esterified with polyhydric alcohols. The plasticized polyvinyl chloride composition is present in an amount of 0.2 to 0.8 parts by weight based on the total weight of the plasticized polyvinyl chloridetreated fabric. The fiber base may comprise an open-mesh gauze fabric but, preferably, is a bundled nonwoven fabric of the type disclosed, for example, in Griswold U.S. Pat. Nos. 3,081,514 and 3,081,515 where the fibers of the nonwoven fabric are bundled together'around openings formed through the fabric.

Patented Sept. 15, 19 70 28, 7 Sheet 2 Gauze ATTORNEY WOUND RELEASE DRESSING BRIEF SUMMARY OF THE INVENTION The present invention relates to surgical dressings and, more particularly, to dressings which possess a low degree of adhesion to the surface of healing wounds over which the same are placed and yet has many of the characteristics of gauze dressings in that the same is readily wetted and is sufficiently abrasive to permit the scrubbing of a wound area in cleaning the same by a physician.

It has generally been recognized that in the natural healing of animal wounds, the dressing serves primarily as a protection for the wound during the healing process. The problem with generally used dressings is that during the healing process the eschar tends to form or grow around parts of the dressing, thus making it difficult later to remove the dressing without tearing the eschar or scab, and thus delaying the healing process. In order to overcome this, it has heretofore been proposed to use a smooth, thin, flexible, nonwater soluble film in direct contact with the wound. The film, which may be made of any smooth, flexible material, is perforated or cut to permit passage of fluids through the film to an absorbent backing. Dressings have accordingly been proposed wherein the flexible, nonwater soluble, perforate film is bonded to or wrapped around an absorbent pad. Also, again utilizing the smooth surface concept for reducing wound adherence, dressings have been proposed made in the manner such as described in U.S. Pat. No. 3,006,338 wherein a fabric, preferably nonwoven, is impregnated with a polyethylene emulsion and then, after removal of the water, heated with one surface in intimate contact with another smooth surface to flatten out the deposits of polyethylene on the surface into smooth, film-like patches giving to the surface a smooth, fiber-free appearance. One of the difficulties with film surfaced dressings is that their rate of absorption is dependent to a substantial degree on the size and number of holes in the film which forms the wound-contacting surface of the dressing. If the holes are too small, there is a tendency for the same to plug, blocking the flow of wound exudate. If the holes are too large, then there is a tendency for the surface of the wound to come in contact with the fibers of the underlying absorbent and bond to the same, thus defeating to a substantial degree the use of the smooth film covering for obtaining nonadherency. A further disadvantage of filmed surface dressings is that in the formation of small dressing pads such, for example, as used in adhesive bandages or other dressing formation where the manufacture of the dressing involves an appreciable amount of folding, the film fiber laminates are difficult to handle and fold with most machinery. Also, many surgeons have been used to using the gauze dressings for wiping and cleaning the area of a wound where the wettable characteristics of the gauze and its slightly abrasive nature help substantially in this cleaning procedure. However, the film surface of the film-faced dressings is completely unsatisfactory for such cleaning because of its smooth and generally hydrophobic nature.

These problems have now been obviated by the discovery that open-mesh fiber base fabrics, when impregnated with a plasticized polyvinyl chloride have excellent wound release characteristics as long as the plasticized polyvinyl chloride is present in amounts of at least 20 percent by weight of the impregnated fabric. Also, such a dressing material wets readily and has sufficient abrasive characteristics to permit its use in cleaning of wound areas. Not only do fabrics so treated have excellent wound release properties as well as wetting and mildly abrasive characteristics, but the same have much the appearance of the treated fabric. Also, the handling qualities of fabric so treated is substantially improved the same being readily handled and folded in the manufacture of dressings of different types. Furthermore, wound exudate readily passes through such dressing materials into backing absorbent where a backing absorbent is used as a part of the dressing.

The preferred plasticizers are the polyesters of long chain poly basic acids esterifled with polyhydric alcohol. These tend to form an eutectic mixture with the polyvinyl chloride which mixture has a flow temperature appreciably above that generally used in the sterilization of dressings and the like by autoclave techniques.

DETAILED DESCRIPTION OF INVENTION In preparing the wound release dressings of the present invention, a base fabrichaving an open mesh of about to 324 holes per square inch is preferably used. Although a low count gauze may be employed, in the preferred practice of the present invention open-mesh nonwoven fabrics of the type described, for example, in Griswold U.S. Pat. Nos. 3,081,514 and 3,081,515 are used. In fabrics of this type, openings are formed through the nonwoven fabric by bundling or bunching of fibers together to form openings with peripheries of bunched or bundled fibers. The perforate, nonwoven fabrics so formed are then generally treated with a binder such, for example, as a viscose binder, to improve the strength of the same. These perforate, nonwoven fabrics may be overall bonded. However, the preferred nonwoven perforate fabrics found most suitable for making the wound release dressings of the present invention are those which have a discontinuous bonding pattern. One of the preferred discontinuing bonding patterns is that illustrated, for example, in the De Witt Ri Petterson et al. U.S. Pat. No. 2,705,687, in which the fibers of a nonwoven web are bonded together by an articulated multisegmented binder pattern, the individual segments of which are separated from, but hingedly connected to, each other by substantially unbonded length of fibers. It is found that with the intermittent or discontinuous bonding of the base nonwoven fabric the same can be more readily folded, with less tendency to spring back, than with overall bonded materials. Also, in the preferred practice, the base fabric has a staggered hole pattern such, for example, as illustrated in FIG. 1 of the present drawings and FIG. 9 of U.S. Pat. No. 3,081,515, rather than a square hole pattern such as is present in gauze or that illustrated, for example, in FIG. 1 of Griswold U.S. Pat. No. 3,081,515, as the staggered hole pattern also gives wound release fabrics that can be folded more readily. However, the shape and staggering of the holes as well as the manner of bonding the nonwoven base fabric relate primarily to the ease in handling the final product with respect to folding in the making of composite dressings utilizing the same and apparently have no effect on the wound release characteristics of the material.

The plasticized polyvinyl chloride is applied by treating with an organic solution of the same. Any of the dispersion grade polyvinyl chlorides such, for example, as QYNV (trade name for a percent polyvinyl chloride polymer of 1.40 specific gravity) may be used.

Examples of commercially available plasticizers are D.O.P. and the polymeric plasticizers sold under the trade name Paraplex. The Paraplex plasticizers are polyester resins based on long chain polybasic acids esterfied with polyhydric alcohols such as glycerol or ethylene glycol. They come in different grades, Paraplex G-50 being one of the preferred. D.O.P. is the name in the trade used for the monomeric plasticizer dioctyl phthalate. Any plasticizer may be used, but the nonmigrating polymeric types are preferred.

The polyester where used as the plasticizer should be present in the polyvinyl chloride-polyester composition in amounts of .6 to 1.0 parts polyester per part of polyvinyl chloride. Small amounts of stabilizer, such for example as dibutyltin maleate, may be added if desired, however, the presence of the same has no apparent effect on the release qualities of the wound release fabric.

in treating the fiber base, a solution is first prepared containing approximately 50 to 80 parts of solvent, 10 to 25 parts of dispersion grade polyvinyl chloride, 10 to 15 parts of polyester, and .3 to 3 parts of stablizer. The solution may be applied by any coating technique such as padding, gravure coating, knife coating, spraying, or the like. However, the preferred practice is to use print coating as better control is obtained of the amount of pickup of coating solution by the base fabric. As the organisol solution is sufficiently fluid to wick into the base fabric, the coating, even though applied by printing in a pattern, is not restricted to the pattern in which it is applied but flows into the base fabric and surrounding fibers bonding together and encapsulating the fibers with which it comes in contact.

After the base fabric has been coated with the organoslo, it is baked for approximately I minute at about 370 to 425F. to drive off the solvent and set the polyvinyl chloride-polyester composition in the fiber base. As previously indicated, the polyvinyl chloride and polyester appear to form an eutectic mixture which has a melting point well above 260F. This permits sterilization of the wound release fabrics by conventional steam sterilization without flow of the organosol to surrounding wrappings.

The practice of the present invention is further described with reference to the drawings in which:

FIG. 1 is a perspective view of a wound release fabric made in accordance with the present invention;

FIG. 2 is a photomicrograph of an enlarged portion of the fabric of FIG. 1;

FIG. 3 is an adhesive bandage utilizing the wound release fabric of FIG. 1;

FIG. 4 illustrates the pad of the bandage of FIG. 1 in manufacture;

FIG. 5 illustrates a dressing that can be used either for cleaning or wound covering;

FIG. 6 illustrates the folding of the dressing of FIG. 5; and

FIG. 7 is a graph illustrating release as function of a composition pickup.

Referring to the drawings, in FIG. 1 is illustrated a wound release fabric 10 which compresses a nonwoven fabric base 11 having openings 12 therethrough formed by the bundling of the fibers 13 around the periphery of the openings to form the same. This is best illustrated in the microphotograph in FIG. 2. The openings 12 are elliptically shaped having a length of approximately 0.075" along the major axis of the ellipse and a width of approximately 0.025" along the minor axis. The same are also staggered with respect to each other which, as previously indicated, is the preferred construction although the invention is not limited thereto. Although the fabric is prepared by print coating technique, it will be noted that the polyvinyl chloride-polyester composition 14 has impregnated into the fabric the composition not only coating a substantial amount of the fibers, but also penetrating into the fibers 13 of the fiber bundles.

The reason for the excellent wound release properties obtained through this construction is not understood as no smooth film surface is utilized as is done in the usual concept of dry wound release dressings. However, substantially better wound release properties are obtained than, for example, can be obtained with a fabric in which the fibers are formed of polyethylene, although polyethylene as a film has excellent wound release properties. The wound release is dependent on the degree of pickup by the fabric treated with the plasticized polyvinyl chloride. Thus, for example, a coating weight of at least 0.2 ounce per square yard with a rayon fabric of 0.7 ounce per square yard is required to give nonadherent properties. As the coating weight is increased, the nonadhering properties, that is the release from healing wound surfaces, substantially improves. This is illustrated in the graph of FIG. 7. Although the best wound release properties are obtained with coating weights as high as 3 ounces per square yard of base fabric where the weight of the base fabric is approximately 0.7 ounces per square yard, it is generally desirable, particularly for small dressings such as used in the absorbent pads of adhesive bandages, that the coating weight not exceed about 1.2 ounces per square yard as higher coating weights appreciably effect the draping qualities of the fabric, the same becoming relatively stiff with coating weights as high as 3 ounces per square yard. Thus on a fiber-plasticized polyvinyl chloride weight basis, the wound contacting surface of the wound release fabric contains from about 0.2 to 0.8 parts by weight of plasticized polyvinyl chloride based on the total weight of the impregnated fibers.

The release characteristics of the wound release fabrics of the present invention as affected by the amount of polyvinyl chloride-polyester composition present is illustrated in the graph of FIG. 7 wherein the same are compared with the wound release property of conventional gauge and of an absorbent-backed perforate Mylar film. These measurements are based on in vitro tests utilizing guinea pig skin freshly removed. Adherence to the raw side of such skin by the wound release fabric is measured by strain gauge after 7 hours contact. This in vitro test method is particularly good for comparing several different wound release fabrics as a substantial portion of the skin can be removed and then cut into small squares of 2.5 cm. x 2.5 cm. permitting good comparative results for several samples, as the skin and conditions are identical. The adherence results shown by the in vitro test correlate well with in vivo tests. The in vivo tests, however, are not as suitable for comparative test screening as only relatively small areas of wound are available for any single animal.

In FIG. 3 of the drawings is illustrated an adhesive bandage 20 having the conventional pressure-sensitive adhesive coated tabs 21 and an absorbent pad 22. Such absorbent pads are generally prepared with a facing fabric such as gauze, or the like which covers an underlying absorbent which may be further folds of gauze, or other absorbent material. One of the preferred pad constructions is that disclosed, for example, in Ganz US. Pat. No. 2,893,388 wherein the covering gauze is folded so as to completely enclose the underlying absorbent, and the ends are folded inwardly to avoid any edges projecting beyond the pad. Such manner of folding is illustrated in FIG. 4, the absorbent 24 being completely enclosed within the overlying fabric 23. In the practice of the present invention the overlying fabric 23 is formed of wound release fabric such as that previously described, an embodiment of which is illustrated in FIGS. 1 and 2.

In FIGS. 5 and 6 is illustrated a nonadherent dressing made in accordance with the present invention which is somewhat similar in construction to the presently available gauze dressings. These dressings generally have a size of anywhere from about 2 x 2 in the folded state to about 4 x 8 inches. The dressings are utilized not only for wound protection purposes but also frequently used for cleaning a wound area by the surgeon. Referring to FIGS. 5 and 6, the dressing 25 comprises a nonwound adhering fabric 26 of the type, for example, illustrated in FIGS. 1 and 2 of the drawing. The fabric 26 is folded over an inner absorbent layer 27 of absorbent fibers such as cotton or the like. The absorbent layer 27 may also consist of cellulosic wadding or a combination of cellulosic wadding and cotton fibers or other suitable absorbent material. The dressing is first folded in the manner of FIG. 5 and then finally folded along line 28 into the form illustrated in the folded dressing of FIG. 6. A plurality of dressings of this type may be used together, one placed on top of the other where it is desired to absorb substantial amounts of wound exudate or a single dressing may be placed over the immediate wound area and then the conventional gauze dressing placed over the same should further absorbent material be needed. Dressings, made in accordance with the present invention, placed in contact with a wound surface present to the wound surface a protective covering which has substantially less tendency to adhere to the underlying wound during the healing process than would the gauze of conventional gauze type dressing and are superior in wound release properties to some of the perforated film dressings.

The final dressing may take many forms in which the wound release fabric is utilized. Thus, the wound release fabric may be used alone as the dressing material or may be placed over the wound and then backed by absorbent, the whole being taped to the patient. One of the big advantages of the wound release fabric, however, is the easy manner in which the same can be handled in preparing composite dressings in which the wound release fabric forms primarily the wound contacting surface. Thus, the wound release fabrics are particularly useful in forming the absorbent pads of adhesive bandages such as illustrated in FIGS. 3 and 4 and larger dressings such as illustrated in FIGS. 5 and 6, where folding is required during the forming process.

The practice of the present invention is further illustrated by the following example which is given for purpose of illustration only, the invention not being limited thereto.

A base material is used comprising a nonwoven fabric consisting of bundled rayon fibers held in place with a viscose binder printed in crosshatch pattern. It has a weight of 0.7 ounces per square yard and contains I65 holes per square inch. An organosol is prepared by mixing until uniform, 400 parts by weight QYNV polyvinyl chloride resin, 303 parts Paraplex G -50 plasticizer and seven parts dibutyltin maleate stablilizer. This is reduced in viscosity by adding 2,800 parts of zylene. The organosol is printed on the fabric by the direct gravure process using an engraved roll having 256 cells per square inch of 16 mils depth, the diameter of the roll being 9 inches. The roll gives uniform impregnation of the web. The impregnated fabric is dried 1 minute at 350 F. and contains a coating weight of 0.5 ounce per square yard. This coated fabric is then slit into supply rolls of the desired width. The fabric is then folded on an adhesive bandage making machine to form an absorbent pad with backing absorbent as illustrated in FIGS. 3 and 4, which is secured to a flexible backing coated with pressure-sensitive adhesive for formation of an adhesive bandage.

Particular embodiments of the invention have been used to illustrate the same. The invention, however, is not limited to these specific embodiments. In view of the foregoing disclosure, variation or modifications thereof will be apparent, it is intended to include within the invention all such variations and modifications except as do not come within the scope of the appended claims.

We claim:

1. In a dressing a perforate fiber fabric having at least one side thereof adapted to contact a wound surface and at least said wound contacting side being impregnated with plasticized polyvinyl chloride in an amount of not less than about 0.2 parts by weight plasticized polyvinyl chloride based on the total weight of impregnated fibers.

Z. A dressing of claim 1 wherein said perforate fiber fabric is a nonwoven fabric.

3. A dressing of claim 2 wherein said nonwoven fabric has the openings therethrough edged by fiber bundles, the fiber bundles being impregnated by plasticized polyvinyl chloride.

4. A dressing of claim 1 wherein said fabric contains dispersed therethrough and as a fiber coating, plasticized polyvinyl chloride said plasticized polyvinyl chloride being present in an amount of 0.2 to 0.8 part by weight based on the total weight of the plasticized polyvinyl chloride impregnated fabric.

5. A dressing of claim 4 in which the fibers of said fabric are rayon fibers.

6. A dressing of claim 1 wherein said perforate fiber fabric is gauze.

7. A dressing of claim 4 wherein said fabric is backed by an I absorbent.

8. A dressing of claim 7 wherein said fabric is folded around said absorbent.

9. A dressing of claim 8 wherein said fabric is a perforate nonwoven fabric having fibers thereof bonded together by an articulated multisegmented binder pattern the individual segments of which are separated from, but connected to, each other by length of fiber substantially unbonded by the binder of said pattern.

10. A dressing of claim 7 wherein said fabric and absorbent are secured to a flexible sheet having at leat a portion thereof extending beyond opposing edges of said fabric and said absorbent to form flexible tabs, said flexible tabs containing a pressure-sensitive adhesive thereon for securing said dressing to a patient.

11. A dressing of claim 10 wherein said fabric is folded around said absorbent.

12. A dressing of claim 1 1 wherein said fabric is a nonwoven fabric having openings, said openings being edged by fiber bundles the fiber bundles being impregnated by plasticized polyvinyl chloride.

13. A dressing of claim 12 wherein said plasticizer is a resin polymer comprising a polyester of long chain polybasic acid esterified with polyhydric alcohol. 

